spoofemptymailbox POP Proxy option is set to
1 (default is 0) and the user's POP server is unavailable, the MMP will simply return an empty mailbox listing. Turning this option on will override the
spoofmessagefile option. We have received reports that this will cause certain clients (including Microsoft® Outlook) to re-download the mailbox when the back-end server comes back online.
The default value is: 0